A pressure accumulator is usually used to compensate for operational pressure fluctuations in a conveying system of a pressure medium, usually engine oil, by storing a certain volume of pressure medium at a predetermined pressure.
Such a pressure accumulator is, for example, filled with the pressure medium via a pressure medium pump during operation of an internal combustion engine of a motor vehicle. If the system pressure supplied by the pressure medium pump drops below a value which is necessary for a fail-safe operation, the pressure medium stored in the pressure accumulator may be emptied into the pressure medium line and is thus immediately available. This makes it possible to compensate for the event of the system pressure dropping below a minimum pressure within the pressure medium system or to increase the volume flow.
For example, such a pressure accumulator may be used to support the pressure supply of a camshaft adjuster. The camshaft adjuster is in this case used in an internal combustion engine of a motor vehicle to be able to variably set the phase relation between a crankshaft and a camshaft in a defined angle range. The camshaft adjuster regularly has an output element which is situated rotatably in relation to a drive element. The drive element is usually in drive connection to the crankshaft; the output element is rotatably fixedly connected to the camshaft. The output element and the drive element essentially delimit at least two pressure chambers acting against one another. By connecting the pressure chambers in a targeted manner to a pressure medium pump or to a pressure medium tank, the phase position of the output element may be set or maintained in relation to the drive element and thus of the camshaft in relation to the crankshaft.
Here, the pressure accumulator may be situated in the camshaft cavity of a hollow camshaft, in particular, and may be communicatively connected to the camshaft adjuster, and, for example, prevent a sudden drop in the adjustment speed during an adjustment procedure. At the beginning of a phase adjustment, a certain quantity of the pressure medium is withdrawn from the pressure medium system of the internal combustion engine. Consequently, the system pressure drops to a lower level. The system pressure present prior to the adjustment is therefore not available to the full extent. This results in the adjustment speed of the camshaft adjuster dropping. This pressure drop is compensated for by the full pressure accumulator, whereby the adjustment speed may be maintained at a high level.
A pressure accumulator of the type mentioned at the outset is known, for example, from DE 10 2009 054 055 A1. Here, the device for supplying pressure designed as a pressure accumulator essentially includes a housing having a housing cavity in which a displaceable element is situated which is designed as a piston and which is displaceable between a first final position and a second final position. The displaceable element is provided with a pressure surface which, together with a housing cavity wall, delimits at least partially a reservoir connectable to the consumer of an internal combustion engine in a fluid-conveying manner. Here, the displaceable element may be displaced from the first final position into the second final position by applying pressure against the force of an energy store. Furthermore, the pressure accumulator has a locking mechanism which is designed as a locking device and using which the displaceable element may be locked in the second final position. The disadvantage here is, however, in particular the implementation of the locking device, whose manufacture and assembly are complex, and the placement of the locking device in the housing in the area of the reservoir directly behind the pressure surface of the displaceable element, which also has an unfavorable effect on the assembly.